Method of applying hydrocarbon barrier to a plastic fuel tank

ABSTRACT

The subject invention relates to a method of applying the hydrocarbon barrier inside plastic fuel tanks. The plastic fuel tanks are supported on a carrier in an upright position for movement in a loop through inverted positions. While upright, hot and dry air treats the inside of the plastic fuel tanks followed by injecting SO 3  inside the plastic fuel tanks through the nozzles. The SO 3  is extracted from the plastic fuel tanks followed by injecting ammonia into the tanks through a second nozzle. After extracting ammonia from the plastic fuel tanks, the tanks are inverted and drained followed by a rinsing with a high pressured water and drying with hot air.

RELATED APPLICATION

[0001] The subject application claims priority to provisionalapplication 60/358,522 filed Feb. 21, 2002.

TECHNICAL FIELD

[0002] The subject invention relates generally to a fuel tankhydrocarbon barrier and, more particularly, to a method of applying thehydrocarbon permeation barrier inside the plastic fuel tanks.

BACKGROUND OF THE INVENTION

[0003] There are several technologies for manufacturing of plastic fueltanks currently available in an automotive industry. One of thetechnologies known in the art includes two or more pieces of coatedsteel combined with classical metal joining technologies. Anothertechnology comprises blow molding of a thermoplastic polymer melt. Themolded plastic tanks are more expensive, but have significant design andflexibility advantages compared with metal tanks. Both technologies donot provide an effective hydrocarbon barrier for a plastic fuel tank.

[0004] There is a big concern with automotive generated pollutants.There is also an immediate need for an improved gasoline tank technologythat would be capable of allowing the use of oxygenated fuel additiveswithout deleterious existing tank technologies.

[0005] Nanocomposites, known to one skilled in the art, may solve thecurrent problem with air pollution and hydrocarbon emissions. Thenanocomposites may slow transmission of gases and moisture vapor throughplastics by creating so called “tortuous path” for gas molecules. Basedon recent EPIC studies, nanocomposites, commercially beneficial, may beused for reducing hydrocarbon emissions from hoses, seals, autofuel-system components and the like. However the use of nanocompositesmay still be expensive.

[0006] Therefore, it would be desirable to come up with a cost and timeeffective method of creating a strong hydrocarbon barrier inside theplastic fuel tanks to prevent hydrocarbon emissions that could causepollution an explosion of a gas tank.

SUMMARY OF THE INVENTION

[0007] The present invention provides a method of applying a hydrocarbonpermeation barrier inside plastic fuel tanks including the steps ofpre-heating the interior of the tank with air, injecting a hydrocarbonbarrier substance into a fuel tank while the tank is upright,withdrawing the barrier substance from the tank, injecting aneutralizing substance into the tank, inverting the tank and drainingthe neutralizing substance, and drying the interior of the tank.

[0008] In order to perform the method the invention includes a conveyorline comprising an endless loop conveyor entrained around a spaced pairof sprockets to create an upper plurality of stations and a lowerplurality of stations. A plurality of carriers support the tanks on theconveyor as each of the carriers include a plate with a holethrerethrough for receiving the spout of a fuel tank. A retainer engagesthe spout of the fuel tank extending through the hole for retaining thetank to the carrier.

[0009] The advantage of the present invention is a cost effective, timeeffective method of applying SO3 with further application of the ammoniato create a strong hydrocarbon barrier inside the plastic fuel tanks.

[0010] The advantages of the invention will become apparent to oneskilled in the art from the following detailed description of thepreferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a plan view of a processing line to process plastic fueltanks;

[0012]FIG. 2 is a side view of the processing line to process plasticfuel tanks;

[0013]FIG. 3 is an end view of a right end of the processing line;

[0014]FIG. 4 is a schematic view of the carriers holding the plasticfuel tanks on the conveyor;

[0015]FIG. 5 is a view similar to FIG. 4 but showing one tank supportedby a carrier; and

[0016]FIG. 6 is a side view of the nozzle use to inject a barrier gasinto the fuel tanks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] Referring to the Figures, wherein like numerals indicate like orcorresponding elements throughout the views, FIGS. 1 and 2 show aprocessing line for processing plastic fuel tanks that includes eightstations, generally shown at 12, 14, 16, 18, 20, 22, 24 and 26. The lineincludes a conveyor 28 entrained around pulleys or sprockets 30 and 32for moving fuel tanks 34 through four stations 14, 16, 18 and 20 alongthe top of the conveyor loop and through four stations 20, 22, 24 and 26along the bottom of the conveyor loop.

[0018] The fuel tanks 34 are loaded and unloaded in groups of eight ontothe conveyor 28 at a loading station 12. As best viewed in FIGS. 4 and5, each fuel tank 34 is supported by a carrier 36 that comprises a pairof legs on each side that are, in turn, supported by the conveyor 28.The conveyor 28 includes a loop on each side with rollers running alongflanges 40 that are supported by the framework of the line. Each carrier36 includes a plate 38 having a hole therein for receiving the nozzle ofthe fuel tank 34. The plastic fuel tanks 34 are loaded in the carriers36 in an upright position and secured within the carriers 36 by aretainer 42. More specifically, the nozzle or spout of each fuel tank isinserted through the hole in the plate 38 of a carrier 36 and a retainer42 threadedly engages the spout to hold the fuel tank to the plate 38 ofthe carrier 36. Each retainer 42 has a tapered lead-in or entry 44 tofacilitate a nozzle, generally shown at 46, to enter the spout.

[0019] The conveyor 28 moves the carriers 36 with the fuel tanks 34supported thereby from the loading station 14 to a pre-heat and/ordrying station 14 where eight nozzles 48 are moved downwardly by anappropriate actuator (hydraulic or pneumatic) and into the spouts of thevarious tanks 34. A timer determines how long the pre-heated air isinjected into the tanks 34 in the pre-heat station 14. Hot and dry airis important to create a dry environment to speed up a chemical reactionwhen SO3 is applied in the next station 16, which is a hydrocarbonpermeation barrier station.

[0020] The barrier station 16 includes a plurality (eight) of thenozzles 46 for injecting SO₃ into and extracted from the plastic fueltanks 34. Although SO₃ is preferred, other suitable fluids, liquid orgas, may be used. The barrier creating SO₃ is stored in a tank 50 forflow through the nozzles 46. The conveyor is stopped by an appropriatecontrol system to align the nozzles 46 with the retainers 42 andappropriate actuators lower the nozzles 46 into the tanks 34 whilesealing the nozzles 46 to the spouts of the tanks 34. The SO₃ is atapproximately fifteen percent (15%) concentration and after circulatingin each tank 34 for a predetermined period of time, is pumped out byapplying a vacuum to the nozzles 46 and extracted by a hood 52 andvented to another storage tank or chemical scrubber (not shown) orallowed to escape via a non restricted opening. The time to create thepermeation barrier depends upon ambient temperature and humidity, theconcentration of the SO₃ gas, the material and size of the fuel tank 34.After the predetermined time of treatment, the nozzles 46 are retractedand the tanks 34 are moved to the next station 18, which is aneutralization station.

[0021] A number of neutralizers can be used but the preferred is aqueousammonia. Another gang of nozzles 54 are lowered into the spouts of thetanks 34 in the neutralizing station 18 where ammonia is injected intothe plastic fuel tanks 34 and pumped out after a short period of time. Atank 53 supplies the ammonia and a hood 55 collects fumes in theneutralizing station 18.

[0022] After neutralizing, the plastic fuel tanks 34 are carried by theconveyor 28 around the end sprocket 32 to an inverted position in adrain station 20 for draining a residue from the respective tanks 34.

[0023] The conveyor 28 moves the inverted tanks 34 from the drainstation 20 to the rinse station 22, which is directly under the barrierstation 16. The inverted plastic fuel tanks 34 are rinsed with a waterby a plurality of nozzles 56 located below the line, which inject thewater into the inverted plastic fuel tanks 34 at a high pressure. Theinverted tanks 34 move into a second drain station 24 and then into thefinal station 26 where blowers 58 subject the interior of the tanks 34to hot air for drying. Finally the tanks 34 are mover around thesprocket 30 to the upright position in the loading and unloading station12 where they are removed by unscrewing the retainers 42 from the spoutsof the tanks 34.

[0024] Referring back to FIG. 6, the nozzle 46 includes different andindependent ports 60 and 62 for injecting and removing the SO₃ throughorifices 64 and 66 respectively.

[0025] A sensor maintains 15% gas, level in monitoring SO₃ during theinjection of SO₃ into the plastic fuel tanks (not shown).

[0026] Accordingly, the invention provides a conveyor line forprocessing plastic fuel tanks 34 to create a hydrocarbon barrier withinthe tanks 34. The line comprises an endless loop conveyor 28 entrainedaround a spaced pair of sprockets 30, 32 to create an upper plurality ofstations 12, 14, 16 and 18 and a lower plurality of stations 20, 22, 24and 26. A plurality of carriers 36 support the tanks 34 on the conveyor28 and each of the carriers 36 includes a plate 38 with a holethrerethrough for receiving the spout of a fuel tank 34. A retainer 42engages the spout of the fuel tank 34 extending through the hole forretaining the tank 34 to the carrier 36.

[0027] A barrier station 16 has a plurality of nozzles 46 for engagingthe retainers 42 and injecting gas into the tanks 34. A neutralizingstation 18 has a second plurality of nozzles 54 for injecting aneutralizing substance into the tanks. At least one drain station 20 or24 is disposed under the aforementioned or first plurality of stationsfor draining the tanks 34 while inverted. Additionally, at least onedrying station 22 or 26 is disposed under the aforementioned or firstplurality of stations for drying the tanks 34 while inverted.

[0028] The method of applying a hydrocarbon permeation barrier insideplastic fuel tanks comprises the steps of pre-heating 14 the interior ofthe tank 34 with air, injecting 16 a hydrocarbon barrier substance intoa fuel tank 34 while the tank 34 is upright, withdrawing 16 the barriersubstance from the tank 34, injecting 18 a neutralizing substance intothe tank 34, inverting 32 the tank 34 and draining 20 the neutralizingsubstance, and drying 22 and 26 the interior of the tank 34.

[0029] The method is particularly defined as holding the fuel tank 34 bya spout of the fuel tank 34 with a conveyor 28 and moving the tank 34through a plurality of stations while held by the spout. The tank ismoved through a first plurality of stations 12, 14, 16 and 18 whileupright followed by being moved through a second plurality of stations20, 22, 24 and 26 while inverted. In the preferred method, a retainer 42having a hole therethrough for receiving a nozzle engages the spout ofthe tank 34.

[0030] In a more specific sense, the method steps include loading aplurality plastic fuel tanks 34 in carriers 36 in an upright position;securing the plastic fuel tanks 34 within the carriers 36 by retainers42 engaging the spouts thereof; placing the carriers 36 with the plasticfuel tanks 34 under a plurality of air nozzles 48; injecting hot and dryair through the air nozzles 48 and into the plastic fuel tanks 34;injecting SO₃ into the spouts of the plastic fuel tanks 34 throughnozzles 46 while sealing the spouts for a predetermined period of time,after which the SO₃ is extracted from the plastic fuel tanks 34 throughthe nozzles while in sealing engagement with the spouts. The continuousflow of SO₃ injected is extracted at the same rate. This station of SO₃injection is the station that determines the timing for all stations.

[0031] Thereafter the method continues by injecting ammonia into theplastic fuel tanks through a plurality of neutralizing nozzles 54;holding ammonia in the plastic fuel tanks for a second predeterminedperiod of time; and extracting ammonia out of the plastic fuel tanks.The plastic fuel tanks are inverted to drain out a residue of ammoniafollowed by rinsing the inside of the inverted plastic fuel tanks withhigh-pressure water and draining the water from the inverted tanks.Finally, the method concludes by blowing a high velocity and heated airinto the spouts of the plastic fuel tanks to remove the residue ofwater.

[0032] The number of carriers 36 vary according to the size and shape oftanks 34 to be processed.

[0033] Obviously, many modifications and variations of the presentinvention are possible in light of the above teachings. The inventionmay be practiced otherwise than as specifically described within thescope of the appended claims wherein the reference numerals are merelyfor convenience and are not to be read in any way as limiting.

What is claimed is:
 1. A method of applying a hydrocarbon permeationbarrier inside plastic fuel tanks comprising the steps of: pre-heatingthe interior of the tank with air, injecting a hydrocarbon barriersubstance into a fuel tank while the tank is upright, withdrawing thebarrier substance from the tank, injecting a neutralizing substance intothe tank, inverting the tank and draining the neutralizing substance,and drying the interior of the tank.
 2. A method as set forth in claim 1further defined as injecting SO₃ as the barrier substance.
 3. A methodas set forth in claim 2 further defined as injecting ammonia as theneutralizing substance.
 4. A method as set forth in claim 1 furtherdefined as holding the fuel tank by a spout of the fuel tank with aconveyor and moving the tank through a plurality of stations while heldby the spout.
 5. A method as set forth in claim 4 further defined asmoving the tank through a first plurality of stations while uprightfollowed by moving the tank through a second plurality of stations whileinverted.
 6. A method as set forth in claim 4 further defined asthreadedly engaging the spout with a retainer having a hole therethroughfor receiving a nozzle.
 7. A method of applying a hydrocarbon permeationbarrier inside a plastic fuel tank having a spout comprising the stepsof: loading a plurality plastic fuel tanks in carriers in an uprightposition; securing the plastic fuel tanks within the carriers byretainers engaging the spouts thereof; placing the carriers with theplastic fuel tanks under a plurality of air nozzles; injecting hot anddry air through the air nozzles and into the plastic fuel tanks;injecting SO₃ into the spouts of the plastic fuel tanks through nozzleswhile sealing the spouts for a predetermined period of time; extractingSO₃ from the plastic fuel tanks through the nozzles while in sealingengagement with the spouts; injecting ammonia into the plastic fueltanks through a plurality of neutralizing nozzles; holding ammonia inthe plastic fuel tanks for a second predetermined period of time;extracting ammonia out of the plastic fuel tanks; inverting the plasticfuel tanks to drain out a residue of ammonia; rinsing the inside of theinverted plastic fuel tanks with high-pressure water; draining the waterfrom the inverted tanks; and blowing a high velocity and heated air intothe spouts of the plastic fuel tanks to remove the residue of water. 8.A conveyor line for processing plastic fuel tanks to create ahydrocarbon barrier within the tanks, the line comprising; an endlessloop conveyor entrained around a spaced pair of sprockets to create anupper plurality of stations and a lower plurality of stations, aplurality of carriers for supporting the tanks on said conveyor, each ofsaid carriers including a plate with a hole threrethrough for receivingthe spout of a fuel tank, and a retainer for engaging the spout of thefuel tank extending through said hole for retaining the tank to saidcarrier.
 9. A line as set forth in claim 8 including a barrier stationhaving a plurality of nozzles for engaging said retainers and injectinggas into said tanks.
 10. A line as set forth in claim 9 including aneutralizing station having a second plurality of nozzles for injectinga neutralizing substance into said tanks.
 11. A line as set forth inclaim 10 including at least one drain station under said aformentionedstations for draining said tanks while inverted.
 12. A line as set forthin claim 10 including at least one drying station under saidaforementioned stations for drying said tanks while inverted.